Transmitter optical assemblies and receiver optical assemblies are known. Each such optical assembly typically includes a housing containing a substrate and an opto-electronic device. The opto-electronic device is electrically connected to a set of electrical contacts on the substrate using wire bonds. This set of electrical contacts on the substrate is in turn electrically connected, also using wire bonds, to first ends of a set of leads disposed within the housing. Second ends of the leads are accessible outside the housing. During manufacture the assembly is connected to a main circuit board carrying an electronic circuit to which the opto-electronic device is to be connected. This connection is effected by means of, for instance, a soldered connection between the second ends of the leads of the assembly and corresponding electrical conductors on the main circuit board.
Optical assemblies are typically used in optical transceivers of telecommunication network equipment and are expected to work for about ten years without any failure. The many levels of interconnections adversely affect the reliability of such assemblies. Furthermore, the opto-electronic device consists of an active light emitting or light receiving surface (or both) that must be accurately positioned so as to be optically aligned with a lens and a fiber receptacle attached to the housing. This alignment needs to be maintained over a range of operating temperatures.
For the foregoing reasons, it is necessary to carefully select the materials of which the optical assembly is fabricated so that thermal expansion will not cause optical misalignment. In addition, the material selected for the housing must allow for dissipation of any heat generated by the opto-electronic device. And the components of the optical assembly must be manufactured with high precision so that linear dimensions are accurate, usually to within about one micron, to prevent a stacking-up of tolerances that would hamper proper alignment.